1. Field of the Invention
This invention relates to an anchor that is adapted to be embedded in a concrete slab to provide a lifting attachment for the slab. In one of its aspects, the invention relates to an anchor for lifting and moving a concrete slab. In another of its aspects, the invention relates to an anchor having a bent flange for providing a lifting attachment for a concrete slab. In another of its aspects, the invention relates to an anchor assembly which comprises a pair of anchor plates having bent flanges adapted to be arranged in facing relationship for forming the anchor assembly to provide a lifting attachment for a concrete slab.
2. Description of the Related Art
An anchor or multiple anchors are generally used in a field in which a precast concrete slab is lifted to move the slab from one position to another position. In some instances, anchors coupled to void assemblies are positioned in the outer portion of a mold space in which wet concrete is poured and cured to form a concrete slab. The void assembly is then detached from the anchors to form a recess leaving an exposed portion of the anchors. The exposed portion of anchors typically has an opening that receives a shackle or other lifting component with a clutch ring or locking bolt.
U.S. Pat. No. 5,596,846 to Kelly discloses an anchor for embedment in a concrete slab to provide a lifting attachment for the member. The anchor comprises an elongate bar having convergent and divergent surfaces wherein the divergent surfaces face outwardly to direct axial pull-out forces imparted to the bar divergently and laterally into a concrete member within which the anchor is embedded. Divergent wings are fixed to and extend laterally from the bar to direct lateral forces imparted to the bar in divergent directions relative to the bar.
U.S. Pat. No. 3,883,170 to Fricker et al. discloses a lifting anchor for embedment in concrete members and a quick release hoisting shackle wherein the anchor takes the form of bars having split divergent ends or ends turned upon themselves to resist pull-out from the slab.
U.S. Pat. No. 4,173,856 to Fricker discloses an anchor element for the tilt-up and transport of prefabricated building components, and employs bars having split divergent ends to resist pull-out. One of the oppositely oriented force-transmitting surfaces engages a surface of the hoisting shackle body during tilt-up, thereby preventing pivoting of the shackle body against the concrete recess which surrounds the exposed portion of the anchor element.
U.S. Pat. No. 4,367,892 to Holt discloses anchors of a T-shaped configuration to resist pull-out and are generally formed by casting. The T-shaped anchors are supported by anchor support member made of plastics.
U.S. Pat. No. 4,580,378 to Kelly et al. discloses anchors that are stamped and embody a pin which extends transversely through the anchor to resist pull-out.
U.S. Pat. No. 4,930,269 to Kelly et al. discloses anchors that are formed of heavy wire stock which is bent into an inverted V-shaped configuration and has integrally formed laterally extending distal ends which are formed by bending and provide resistance to pull-out.
Anchors are typically made of bar stock which is strong but difficult to work. Three dimensional configurations, such as anchors with wing attachments, have several disadvantages. Anchors having three dimensional structures typically require more complicated manufacturing steps. For example, the anchors with wing attachments can require additional steps, such as welding of wing to the anchor bar. Additional manufacturing steps can also lead to the high manufacturing cost, which reduces productivity.